The present invention relates generally to a shutter for a camera and, more particularly, to a shutter for a camera capable of opening and closing a shutter opening in a reduced time period.
A conventional shutter for a camera is shown in FIG. 9. A drive pin 27 is provided on a drive lever 26 pivoted by a rotor shaft 23a of an actuator 20 and the drive pin 27 penetrates through elongated holes 24b and 25b formed in shutter sectors 24 and 25. As shown in the enlarged view of FIG. 10, the drive pin 27 is slidably engaged with the elongated through-holes 24b and 25b. 
The conventional construction described above ensures that when the drive lever 26 is pivoted by the rotor shaft 23a and the drive pin 27 starts moving, movement of the drive pin 27 is immediately transmitted to the shutter sectors 24 and 25. In FIG. 6, movement of the rotor is shown by a graph in which the ordinate designates the amount of movement of a respective shutter sector and the abscissa designates time. According to the conventional construction in which the drive pin 27 is slidably engaged with the elongated through holes 24b and 25b, the shutter sectors are operated simultaneously with the starting movement of the rotor. At an initial stage of the starting movement of the rotor, the rotor has not yet sufficiently accelerated. Therefore, only an extremely small movement of the shutter sectors is achieved during the initial time period. However, after the rotor has been sufficiently accelerated, the movement amount of the shutter sectors is rapidly increased. If the necessary movement distance of the shutter sectors is designated by notation L1, a time period of t1 is needed to achieve the movement distance L1.
As shown in FIG. 6, in the conventional structure described above, at the initial stage of movement of the rotor, the amount of movement of the shutter sectors is extremely small. Therefore, a relatively large time period t3 is needed to achieve a small amount of movement. A substantial portion of the total time period t1 is taken up by time period t3, thereby substantially increasing the time needed to achieve the necessary movement distance L1 of the shutter sectors. The loss of operating time period occupied by time period t3 is fairly significant.
The present invention provides a shutter for a camera having a structure effective for preventing the loss of operating time period associated with the prior art to achieve a desired movement distance of a shutter sector in a short period of time.
According to one aspect of the present invention, there is provided a shutter for a camera comprising a base plate having a shutter opening formed therein, a shutter sector capable of opening and closing the shutter opening, an operating member for operating the shutter sector, and an actuator for driving the operating member. The operating member penetrates a through-hole provided in the shutter sector, and the through-hole has a size sufficient to drive the operating member substantially in a no-load state immediately after starting to drive the operating member.
By driving the operating member in the no-load state immediately after starting to drive the operating member and at a point in time when the operating member has not yet reached full acceleration, slow operation of the shutter sector is avoided. By operating the shutter sector immediately thereafter, a desired amount of movement of the shutter sector can be achieved in a short period of time.
According to another aspect of the invention, there is provided a shutter for a camera comprising a base plate having a shutter opening formed therein, a shutter sector capable of opening and closing the shutter opening, an operating member for operating the shutter sector, a start member for operating the operating member, and an actuator for driving the start member. A gap is provided between the start member, and the operating member the gap having a size sufficient for driving the start member substantially in a no-load state until the start member is brought into contact with the operating member.
Preferably, the operating member or the starting member is provided such that a width of the region in which the operating member or the starting member is driven in the no-load state immediately after starting to drive the operating member or the starting member can be adjusted.